Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Abstract]
Rental and other revenues	$ 828,929	$ 768,007	$ 736,900
Total net operating income	569,123	531,571	505,075
Reconciliation to net income:
Depreciation and amortization	(287,610)	(259,255)	(241,585)
Impairments of real estate assets	(36,515)	0	(1,778)
General and administrative expenses	(42,266)	(40,553)	(41,031)
Interest expense	(105,385)	(85,853)	(80,962)
Other income/(loss)	1,530	1,394	(1,707)
Gains on disposition of property	63,546	174,059	215,897
Equity in earnings of unconsolidated affiliates	1,535	1,947	4,005
Net income	163,958	323,310	357,914
Total Assets	6,063,376	5,695,138
Office Atlanta, GA [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	143,904	143,612	146,704
Total net operating income	92,297	94,122	95,448
Reconciliation to net income:
Total Assets	928,406	947,877
Office Charlotte, NC [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	73,721	49,347	35,733
Total net operating income	55,689	38,464	28,431
Reconciliation to net income:
Total Assets	984,075	771,121
Office Nashville, TN [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	174,341	149,674	138,089
Total net operating income	129,217	110,039	99,901
Reconciliation to net income:
Total Assets	1,290,819	1,294,178
Office Orlando, FL [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	54,802	51,281	49,459
Total net operating income	32,331	31,301	29,546
Reconciliation to net income:
Total Assets	287,950	285,781
Office Raleigh, NC [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	182,990	162,115	128,189
Total net operating income	134,904	121,005	95,926
Reconciliation to net income:
Total Assets	1,288,878	1,269,200
Office Richmond, VA [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	43,084	45,941	48,079
Total net operating income	28,879	31,726	33,667
Reconciliation to net income:
Total Assets	196,435	202,488
Office Tampa, FL [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	94,726	97,954	99,520
Total net operating income	59,691	64,396	67,059
Reconciliation to net income:
Total Assets	493,966	514,303
Other Segment [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	61,361	68,083	91,127
Total net operating income	36,115	40,518	55,097
Reconciliation to net income:
Total Assets	592,847	410,190
Office Total Segment [Member]
Segment Reporting Information [Abstract]
Rental and other revenues	767,568	699,924	645,773
Total net operating income	533,008	491,053	$ 449,978
Reconciliation to net income:
Total Assets	$ 5,470,529	$ 5,284,948